Cold outreach operates with no prior consent and therefore no goodwill. Every technical and behavioral signal, including sender reputation, is weighted more heavily by mailbox providers.
What sender reputation is#
Sender reputation is the score mailbox providers assign to a sending domain and IP based on complaint rates, bounce rates, engagement, spam-trap hits, and authentication history. It determines whether mail is delivered, filtered, or rejected.
Why it matters#
Reputation is the dominant factor in inbox placement. Content matters far less than the trust a provider has in your domain.
Applying sender reputation to outbound#
- Register in Google Postmaster Tools and Microsoft SNDS to see your domain and IP reputation directly.
- Keep spam complaints below 0.1% (Gmail's threshold is 0.3% for enforcement) and hard bounces below 2%.
- Segment by engagement and stop sending to contacts inactive for 90+ days.
- Authenticate with SPF, DKIM, and DMARC so reputation accrues to your domain rather than a shared IP.
- Ramp volume gradually after any pause longer than two weeks.
Outbound-specific guardrails#
- Send from secondary domains, never the primary company domain.
- Cap each mailbox at 30 to 50 sends per day.
- Stop sequences on any reply, including informal opt-outs.
- Track reply rate as your primary quality metric.
Common mistakes#
- Buying or scraping lists, which seed spam traps into your database.
- Blasting an entire list after months of silence.
- Ignoring Postmaster Tools until placement has already collapsed.
Frequently asked questions#
Domain reputation vs IP reputation: which matters more?
Domain reputation now dominates at Gmail and Yahoo. IP still matters for Microsoft and for dedicated-IP senders.
How long does it take to repair a bad reputation?
Four to eight weeks of clean, low-volume sending to engaged recipients is typical.